One aspect of the present description relates to a method of supplying power to a sensor arrangement which has a first and at least one second sensor, and a sensor arrangement having a first and at least one second sensor.
One aspect of the invention relates to sensor arrangements for detecting the steering angle or steering wheel position in an EPS system (electric power steering) for motor vehicles. In such systems, there are a number of sensors for detecting the steering position which need electric power for generating a sensor signal. Such sensors are, for example, gyromagnetic sensors having four sensor elements and at least one magnet. The four sensor elements are connected together to form a full bridge, the center tap of this full bridge forming the output signal of the sensor. In a steering system, the individual sensor elements and the magnet are arranged, for example, in such a manner that the sensor output signal, in the case of a rotating steering wheel or a rotating steering column, corresponds to a sinusoidal signal, the evaluation of which enables the steering wheel position to be determined. Precise evaluation requires that the maximum and minimum values, between which the output signal is sinusoidal, are constant. This is achieved by supplying the sensors, during a normal operating mode of the sensor arrangement, with a constant voltage for supplying power, for example from a voltage control arrangement.
When the vehicle is parked, a precise determination of the steering wheel position is not required, in principle, but it must be possible to recognize whether the steering wheel is completely rotated by one or more revolutions when the vehicle is parked. For evaluating a complete revolution, it is sufficient to evaluate the zero transitions of the sinusoidal sensor signal. The requirements with respect to the amplitude value and the constancy of the amplitude value of the sensor signal are not as high as during normal operation. During this standby mode, much lower amplitudes of the sensor signal than during normal operation are sufficient. The zero transitions of this signal can still be evaluated for detecting complete steering wheel revolutions.
In order to save electrical power during the standby mode, in comparison with normal operation, it is known to disconnect the individual sensors of such a sensor arrangement from the controlled voltage supply during the standby mode and to connect them to in each case a constant current source. The power consumption of this sensor arrangement during standby mode is then dependent on the sum of the currents supplied by the individual constant current sources.